Question

I would like to know how to parse several double numbers from a string, but string can be mixed, for instance: String s = "text 3.454 sometext5.567568more_text".

The standard method (Double.parseDouble) is unsuitable. I’ve tried to parse it using the isDigit method, but how to parse other characters and .?

thanks.

Answer 1

After parsing your doubles with the suitable regular expressions like in this code or in other posts, iterate to add the matching ones to a list. Here you have myDoubles ready to use anywhere else in your code.

public static void main ( String args[] )
{
    String input = "text 3.454 sometext5.567568more_text";
    ArrayList < Double > myDoubles = new ArrayList < Double >();
    Matcher matcher = Pattern.compile( "[-+]?\\d*\\.?\\d+([eE][-+]?\\d+)?" ).matcher( input );

    while ( matcher.find() )
    {
        double element = Double.parseDouble( matcher.group() );
        myDoubles.add( element );
    }

    for ( double element: myDoubles )
        System.out.println( element );
}